(a) Technical Field
The present disclosure relates to a control method and system for preventing a motor from overheating when a transmission mounted electric device (TMED) hybrid vehicle is driven. More particularly, it relates to a control method and system for preventing performance from deteriorating due to a motor overheating when a TMED hybrid vehicle is driven in an electric vehicle (EV) mode.
(b) Background Art
A hybrid vehicle is an environmentally-friendly vehicle that uses an engine and an electric motor as power sources. In general, the hybrid vehicle is driven by the electric motor using battery power until the vehicle reaches a predetermined speed after the vehicle starts, and driven by properly combining motor power and engine power based on a driver intention and a battery state.
A transmission mounted electric device (TMED) hybrid vehicle is a hybrid vehicle that adopts a TMED, and the electric motor is mounted within the TMED hybrid vehicle to be attached to a transmission. In other words, the electric motor is disposed between an engine clutch and the transmission. The TMED hybrid vehicle is also driven by the electric motor using battery power until the vehicle reaches a predetermined speed after the vehicle starts, and a driving mode of the TMED hybrid vehicle is classified into a hybrid elective vehicle (HEV) mode in which both the engine and the electric motor are driven, and an EV mode in which the electric motor is driven.
Meanwhile, a TMED HEV and a plug-in hybrid electric vehicle (PHEV) in the related art are driven in the EV mode by utilizing electrical energy accumulated in the battery to be controlled with optimum fuel efficiency when a sufficient amount of electricity remains in the battery. In addition, the vehicle performs regenerative braking by utilizing a motor having a high capacity under a driving condition in which driving power is not separately required, thereby achieving improved fuel efficiency compared to the existing general vehicle by the hybrid operation.
However, when the vehicles are driven at substantially high speeds or with substantially high output by the electric motor, an amount of heat emitted from the motor increases, and when a temperature of the motor increases to a predetermined level or greater, the engine is operated regardless of the driver intention, or limitations may exist in maintaining driving performance due to limited output caused by the overheating of the motor.
In other words, when the motor is overheated at a predetermined level or greater when the TMED hybrid vehicle in the related art is driven in the EV mode at substantially high speeds or with substantially high load, an operation of limiting motor power is performed to protect a motor system, output of the motor is limited, and as a result, the engine compensates for insufficient power.
However, when the engine is suddenly operated regardless of the driver's intention due to deterioration in output of the motor, it may not be possible to achieve driving power required by the driver until driving power from the engine is sufficiently transmitted to the wheels, and as a result, there is a limitation in allowing the engine to be operated in a linear manner. Further, the vehicle may not be driven with maximum output due to a limitation of motor output, that is, until the motor is cooled to a predetermined level or greater.
In particular, for the PHEV, an amount of heat emitted from the motor is further increased when the vehicle is driven in the EV mode with a high load utilizing the motor and the battery having a high capacity compared to the existing HEV, and as a result, an alternative for solving the overheating problem of the motor when the vehicle is driven is considered relevant to improving the driving system.
The above information disclosed in this section is merely for enhancement of understanding the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.